CN106175600A - The method controlling mobile robot - Google Patents

Abstract

A method of controlling a mobile robot, the method comprising: monitoring a first system of the mobile robot to detect a first error associated with the first system; and monitoring a second system of the mobile robot to detect a first error associated with the second system A second error in conjunction, wherein when the first error and the second error are simultaneously detected, it is determined that the third error has occurred.

Description

Method for controlling a mobile robot

technical field

The invention relates to a method for controlling a mobile robot and to error detection on a mobile robot.

Background technique

Mobile robots are becoming more common and are used in fields as diverse as space exploration, lawn mowing, and ground cleaning. Recently there has been rapid progress in the field of robotic vacuum cleaners, the main goal of which is to autonomously and quietly maneuver and clean a user's room while requiring as little and preferably no assistance from a human user as possible.

In performing this task, robotic vacuum cleaners must be able to navigate autonomously and overcome obstacles within their environment, and also be able to provide a good level of cleaning performance on many different floor types. For example, it is expected that a single robotic vacuum cleaner will be required to clean most rooms in a typical room environment and should be able to provide a good clean on floor surfaces such as tile, hardwood, thin and thick carpet, floors, etc. performance.

It can be expected that during manipulation, the robot will from time to time encounter problems. For example, robotic vacuum cleaners can suck in large objects (which cause blockages in the air flow through the machine), cables can get wrapped around brush bars, or the like. Often, such problems will require human intervention in order to clear the problem and set the robot back to normal. However, any human intervention required may be considered annoying by the user, and this is preferred if it is possible for the robot to be able to resolve the error itself without any human intervention.

Contents of the invention

The present invention provides a method of controlling a mobile robot, the method comprising: monitoring a first system of the mobile robot to detect a first error associated with the first system; and monitoring a second system of the mobile robot to detect an error associated with the first system; A second error associated with the second system, wherein when the first error and the second error are detected at the same time, it is determined that the third error has occurred.

This method (although specified above for controlling a mobile robot) can be used in the control of other devices such as vacuum cleaners, hair care products and other consumer electronics.

As a result, the bot is able to more precisely determine errors experienced by the bot, and can thus better identify error states that it can resolve itself without requiring user interaction with the bot. This improves the autonomy of the mobile robot and enhances the user experience of the mobile robot.

The method also includes causing the robot to perform an error handling operation in response to a determination that a third error has occurred. By resolving the error itself, the robot will not require any human intervention. As a result, the mobile robot can perform its assigned tasks more efficiently and autonomously.

The error handling operation performed in response to the third error may be different than the alternate error handling operation performed in response to one of the first or second errors. As a result, the most appropriate error handling actions can be specified to solve a particular problem identified by the mobile robot.

The first system may be a floor cleaning system and may include a motor for generating air flow through the mobile robot. As a result, robotic vacuum cleaners may be provided with improved autonomy. In this case, the first error may be a blockage of the gas path, and detection of the first error may include detecting a decrease in load experienced by the motor. A decrease in load can be detected by sensing an unexpected increase in motor speed.

The second system may be a drive system and includes one or more navigation sensors to monitor the position of the robot in the environment and drive actuators to move the robot in the environment. In this case, the second error may be a slip, and the step of monitoring the second system may include monitoring a change in the position of the robot while the robot is being driven. Then, the detection of the second error may include detecting that the change in position of the robot detected by the one or more navigation sensors does not correspond to an amount driven by the drive actuator.

The third error may be the suction state of the robot. The determination of suction state errors will allow the mobile robot to better solve problems where the level of suction generated by the mobile robot adversely affects the mobility of the mobile robot.

The first system may include a motor for generating air flow through the mobile robot, and wherein the error handling operation in response to a determination that a third error has occurred includes operating the motor in a reduced power mode to reduce suction and continue to drive the robot . As a result, during error handling operations, the motors will not generate enough suction to prevent the mobile robot from maneuvering, but will continue to generate some air flow through the mobile robot while the mobile robot is able to navigate away from where the third error occurred area of the ground surface.

The motor is operated in a reduced power mode until the mobile robot has traveled outside a calculated area of predetermined size, the center of which is the location where the third error was detected. This allows the mobile robot to travel away from the area where the error occurred so that it is less likely that a third error will repeat itself when the motors return to normal power levels.

If an instance of one or the other of the first or second error is detected while another instance of the first or second error continues to occur, the first error and the second error may be detected at the same time. As a result, the mobile robot is better able to distinguish between first or second errors and third errors.

The present invention also provides a mobile robot, including a control system, a task execution system, and a drive system, the control system is configured to monitor the task execution system and the drive system, wherein the control system includes an error detection unit, and the error detection unit is Configured to detect a first error in the task performance system and a second error in the drive system, and further configured to determine that a third error has occurred if it detects the first error and the second error at the same time.

As a result, an improved mobile robot is provided to better differentiate between the different errors it encounters.

The control system also includes an error handling unit configured to perform one of the first or second error handling operations in response to detection of a corresponding first or second error, and is further configured to respond to a third error having A determination that occurred instead performs a third error handling operation. As a result, the mobile robot can assign more appropriate error handling tasks to handle the detected errors. This also allows it to handle and clean up more errors autonomously without user intervention.

The task performance system may be a floor cleaning system including a motor for generating air flow through the mobile robot. This allows mobile robots, such as robotic vacuum cleaners, to operate more efficiently and autonomously. The first error may be airway blockage, the second error may be slipping, and the third error may be the adsorption state of the mobile robot.

The present invention also provides an error detection unit for a mobile robot, the error detection unit comprising: a monitoring unit and an error determination unit, the monitoring unit being used to monitor one or more parameters of the first and second systems of the mobile robot , and identifying one or more parameters of the first and second systems that indicate an error, the error determination unit is capable of determining: if the monitoring unit identifies a parameter of the first system that indicates an error, then the first error has occurred; if the monitoring unit identifies a parameter that indicates an error erroneous parameters of the second system then a second error has occurred; if the monitoring unit identifies at the same time parameters indicating erroneous first and second systems then a third error has occurred.

The previously described control system and error detection unit can also be employed in devices other than mobile robots. For example, they may find use in vacuum cleaners, hair care appliances, and other such consumer electronics.

Description of drawings

In order that the present invention may be more easily understood, embodiments of the present invention will now be described by way of example with reference to the following drawings, in which:

Fig. 1 is the schematic diagram of mobile robot;

2 is a schematic diagram of an error detection unit;

Fig. 3 is the schematic diagram of ground cleaning system;

Fig. 4 is the schematic diagram of driving system;

Figure 5 is a robot vacuum cleaner;

6 is a flowchart outlining a method of controlling a mobile robot;

7 is a flow chart outlining a method of handling errors detected by a mobile robot;

Figure 8 is a schematic diagram of a first error handling operation; and

FIG. 9 is a schematic diagram of a second error handling operation.

detailed description

Certain embodiments described herein enable a mobile robot to better determine errors that affect its intended operation. These embodiments enable a robot to specify more appropriate error handling actions in order to handle the error. In certain embodiments described herein, error handling operations may be performed allowing the robot to handle the error autonomously by itself without any assistance from a human user.

The mobile robot 1 shown schematically in FIG. 1 has a control system 2 , a task execution system 3 and a drive system 4 . The control system 2 includes an error detection unit 20 and, in some embodiments, may also include an error handling unit 21 . An embodiment of an error detection unit 20 is shown in FIG. 2 . The error detection unit 20 in FIG. 2 includes a monitoring unit 22 which monitors the task execution system 3 and the drive system 4 of the task mobile robot 1 . The monitoring unit may monitor parameters of systems in the mobile robot 1 and identify parameters indicative of errors within those systems. This identified parameter can then be used by the error determination unit 20 to determine which error has occurred.

The task performance system 3 is a system provided to the robot for performing tasks assigned to the mobile robot. For example, the mobile robot 1 could be a robotic lawnmower, in which case the task performance system 3 would be a grass cutting and/or collecting system. In another embodiment, the mobile robot 1 can be a robotic floor cleaner and the task performance system 3 will be a floor cleaning system. A schematic diagram of such a floor cleaning system 30 is shown in FIG. 3 . The vacuum cleaning system 30 includes a cleaner head 32 , a separation system 33 and a vacuum motor 34 . These structures of floor cleaning systems are common structures of floor cleaning systems and no further description of these systems will be provided herein. Other embodiments of the task performance system will be apparent.

The drive system 4 enables the mobile robot to maneuver and navigate around the environment in which it has to perform the tasks it has set. A schematic diagram of the drive system is provided in FIG. 4 . The drive system 4 is provided with a drive actuator 40 and a navigation sensor 42 . The drive actuator 40 can eg drive wheels or tracks and can provide travel measurements to the control system 2 of the mobile robot 1 . These travel measurements can be used by the control system 2 to estimate the distance and path traveled by the mobile robot 1 . The navigation sensor 42 is a sensor capable of providing information about the environment surrounding the mobile robot 1 to the control system 2 . For example, the navigation sensor 42 can be a visual camera, a proximity sensor, or a laser range finder. The mobile robot 1 will typically use many different types of navigation sensors in order to be able to more successfully navigate autonomously within the environment. The navigation sensor 42 provides information about the environment surrounding the robot 1 to the control system 2 enabling the control system 2 to build a map of the environment which can be used by the mobile robot 1 for navigation. In some embodiments, the navigation sensor 42 may form part of the navigation engine of the mobile robot 1 . Such navigation engines may share some aspects and functions of the control system 2 . In another alternative embodiment, some functions of the control system 2 may be shared across other systems of the mobile robot 1 . For example, each system in the mobile robot 1 may be able to monitor its own parameters and identify parameters 3002 that indicate an error

Figure 5 shows an example of a mobile robot. The mobile robot is a robotic vacuum cleaner 50 and has a floor cleaning system comprising a cyclone separation system 52 and a cleaner head 54 . A vacuum motor (not shown) is provided within the main body of the robotic vacuum cleaner 50 which draws dirty air from the cleaner head 54 through the cyclone separator 52 where the dirt particles are removed from the air flow, and Clean air is then exhausted through vent holes (not shown) in the back of the robot. The robotic vacuum cleaner 50 has drive actuators (in the form of tracks 56 ) that can be driven to move the robotic vacuum cleaner 50 around the environment in which the cleaner is located. The robotic vacuum cleaner 50 has navigation sensors that include a 360 degree panorama ring lens camera 58 capable of capturing images of the area surrounding the robotic vacuum cleaner 50 . The robot's control system uses simultaneous localization and mapping (SLAM) techniques on the images captured by the camera 58 in order to build a map of the environment and identify the robot's position within the map. The SLAM technique performed by the control system also uses travel measurements provided by the driven tracks, and information provided by other sensors such as proximity sensors located in sensor housings 59 positioned on either side of the cyclone 52 .

Robot vacuum cleaners typically have small vacuum motors that don't generate a lot of suction. However, as vacuum motors improve and decrease in size over time, robotic vacuum cleaners may be provided with more powerful vacuum motors. This provides better suction for the robotic vacuum cleaner, which results in improved cleaning performance. Of course, if the robot vacuum cleaner has too much suction, then it is possible that the suction could negatively affect the robot's maneuverability. In fact, if enough suction was generated by the vacuum motor, the robot would suck itself into the ground surface with such force that the drive system would not be able to move the robot. This is often referred to as the "limpet state". When a robotic vacuum cleaner experiences a suction state error, the robot's wheels or tracks will spin on the ground surface, but the robot will not move due to the force with which the robot is sucked to the ground surface by the suction force.

As already explained, the error detection unit 20 of the control system 2 may monitor parameters provided to the control system 2 by other systems within the mobile robot 1 . For example, floor cleaning system 30 may provide an indication of the load experienced by vacuum motor 34 . If there is a blockage in the air path through the floor cleaning system 30, the pressure across the system will decrease and the drop in load experienced by the vacuum motor will be evident in the parameters, for example, there may be an unexpected increase in motor speed . Error handling system 21 can then perform appropriate error handling operations in order to resolve the problem. For a blockage of the gas path, the error handling action will typically be to stop the cleaning operation, stop all movement of the robot 1, and present the error to the user. The user is then guided to find and clear the blockage, and the robot 1 is then allowed to resume cleaning operations.

Another example of an error that may be handled by the error detection unit 20 is a "slip". A slippage error occurs when the drive actuator 40 of the mobile robot tries to move the robot, but the robot does not move. This may, for example, be due to the robot having been maneuvered into an area where the drive actuator 40 is not effectively abutting the ground surface, or it may also be due to the mobile robot itself being navigated onto an obstacle which is rising upwards. The high body is such that the drive actuator 40 can no longer make contact with the ground surface, commonly referred to as "grounding". This slippage error can be detected by the error detection unit 20 because the travel measurements received by the control system 2 are not correlated with the information provided by the navigation sensor 42 . For example, drive actuator 40 travel measurements indicate that the mobile robot should have moved a distance of 0.5 meters in the forward direction, but navigation sensors 42 show that the robot has not moved at all or much less than expected. In response to a slippage error being detected, the error handling unit 21 may again cause the robot to perform appropriate error handling operations in an attempt to resolve the error. For slippage errors, the error handling action may be to stop the robot 1 and present the error to the user. The user can then investigate the problem and deal with the error by picking up the robot and placing it on a different part of the ground surface.

Both instances of the error above require user input to help resolve the error. As already explained above, any need for a user to interact with an autonomous robot is undesirable. Not all errors require user involvement in error handling operations, and if the mobile robot can more precisely and accurately identify errors, more appropriate error handling operations can be assigned to handle that particular error.

Regarding the snapping state error above, there is not a single parameter that instructs the robot to go into a snapping state. However, the adsorption state will cause both clogging and slipping errors to be indicated. Therefore, when the robot enters the adsorption state, both jamming and slipping errors will be detected. Both error handling actions for these two errors require user interaction with the bot, as explained previously. However, it is possible for the bot to handle snap state errors itself, without user intervention. Therefore, an improved method of identifying errors in mobile robots will now be described, which can be used to better distinguish between different error types. In particular, the improved method is able to distinguish between one of a jam error and a slip error and an adsorption state error.

Figure 6 is a flowchart outlining a method of identifying errors in a mobile robot. In this approach, it is recognized that monitoring parameters in the system may falsely identify errors in the system when in fact different error occurrences cause the same parameters. In the method of Figure 6, information about errors detected in other associated systems can be used to better pinpoint and determine the actual errors that have occurred. The method starts by monitoring parameters of the mobile robot's system. If the error is detected in the first system, the next step is to check whether the error is also detected in the second system. If there are no errors in the second system, it may be determined that the first error has occurred. Likewise, if the error is detected in the second system, the next step is to check whether the error is also detected in the first system. If there are no errors in the first system, it may be determined that a second error has occurred. However, if in either case an error is detected also in the other of the first or second system, it may be determined that a third error has occurred which is different from either of the first or second errors.

As already mentioned, snap state errors are examples of errors that manifest themselves as composition or other errors. The method described above will now be applied to the example of a suction state error in a robotic vacuum cleaner. In a robot vacuum cleaner, the first system is a floor cleaning system and the second system is a drive system. A first error associated with the floor cleaning system may be the air blockage described above, and a second error associated with the drive system may be a slip error. When the suction of the robot vacuum cleaner causes the robot to suck itself to the floor, the suction opening of the cleaner head will be drawn into close contact with the floor surface and a seal will be created between the cleaner head and the floor surface. As a result, it will be very difficult to suck air into the suction opening and a partial vacuum will be created inside the cleaner head. This in turn will reduce the load on the vacuum motor and the operating speed of the motor will increase. A control system that will monitor the parameters of the vacuum motor will detect a clogging error in the floor cleaning system.

The second system in a robot vacuum cleaner is the drive system. An error associated with the drive system is a slip error. When the suction of the robotic vacuum cleaner causes the robot to suck itself to the ground, the force with which the robot sucks itself to the ground outweighs the drive force provided by the drive actuators (in this embodiment, driven tracks). Thus, the tracks will turn, but will slip on the ground surface and the robotic vacuum cleaner will not move. Navigation sensors on the robot will recognize that the robot is not moving, and a control system monitoring parameters from the drive system will detect that the motion of the wheels does not coincide with the lack of motion identified by the navigation system. The control system will thus detect slip errors in the drive system.

Following the method shown in Figure 6, if the control system detects an error in the first system, i.e. an airway blockage in the floor cleaning system, before determining that an error has occurred, it first checks for an error in the second system, That is, whether a slip error is detected in the drive system. If no slippage error is detected, then the control system can determine that an air blockage has occurred. However, if a slip error is detected in the drive system, the control system may determine that a suction state error has occurred. The same happens in reverse: if a slippage error is first detected in the drive system, then the control system will check for an air blockage error in the floor cleaning system. If no blockage error is detected other than a slip error, the control system will determine that a slip error has occurred. However, if an air blockage error is detected simultaneously with a slippage error, the control system will determine that an adsorption state error has occurred.

As soon as an error is detected in the first or second system (first error), the control system of the robotic vacuum cleaner is configured to immediately look for an error in the other of the first or second system (second error). The control system may determine that a first error has occurred if no second error is immediately detected in other systems following the detection of the first error. This allows the robot to act quickly in response to errors, but increases the likelihood of errors being misidentified. Alternatively, the control system of the vacuum cleaner may be configured to continue to run the robotic vacuum cleaner for a short period of time (eg, 2 seconds) following detection of the first error, in order to allow the second error to occur. This alternative configuration requires the robot to run while the error state persists, however it also increases the likelihood that the first and second error will be detected at the same time, and thus the third error state (ie the snap state) will be determined. Thus, while a suction state error is more likely to be determined, the robotic vacuum cleaner is also more able to handle error states autonomously by itself without requiring user input.

Once a snap state error has been determined, the robot's control system may cause the robot to perform error handling operations specifically for clearing the snap state error autonomously. One embodiment of error handling operations for autonomously clearing snap state errors is depicted in the flowchart in FIG. 7 .

The method in FIG. 7 begins with the determination of a third error, as determined at the end of the flowchart in FIG. 6 . The third error is a snap status error in this embodiment, however it should be understood that this error handling operation may be performed in response to other errors as well. After the error determination, a region of predetermined size is calculated from the navigation map. The suction force of the vacuum motor is then reduced. This can be done by reducing the power to the motor which reduces the rotational speed of the motor. The motor can, for example, be provided with some power map, which can be used to control the vacuum motor. Power reduction can thus be achieved by selecting a different power map to control the motor. Other methods of reducing the suction force of the vacuum motor will be apparent. As the suction level is reduced, the robot should then be free to move, and thus the robot is then controlled to continue driving on the path it is on. The cleaning operation performed by the robot before the suction state error is continued except that the amount of suction of the vacuum motor is reduced.

Once the suction force of the vacuum motor has been reduced, as the robot moves along its travel path, the control system keeps checking to see if the robot has been traveled outside the previously calculated area in the navigation map. If the robot remains within the previously calculated area, the robot continues to follow its travel path and no other changes are made. However, once the robot leaves the previously calculated area, the suction force of the vacuum motor is increased. This increase returns the suction force to the same level as before the suction state error was detected. Alternatively, the suction force may be increased in stepwise increases over a period of time until full suction force is achieved. The robot then continues with standard operation.

Two examples of a robotic vacuum cleaner 50 performing error handling operations and following the method of FIG. 7 are shown in FIGS. 8 and 9 . The robotic vacuum cleaner 50 follows a travel path 60 (which is a square spiral pattern). The point at which the adsorption state error is determined is indicated by the symbol "X" and is marked with the reference letter L. The control system begins error handling operations at this point. At this point, the robot's control system calculates an area A of predetermined size, and reduces the vacuum motor suction force to enter a low power mode. The robotic vacuum cleaner then resumes traveling along its usual path. With the suction motor running in low power mode, the suction generated will not be sufficient for the robot to suck itself up to the ground surface and the robot can move around the environment as normal. In FIG. 8, the calculated area A is a circular area having a diameter of 1 meter, whereas in FIG. 9 the calculated area A is a 1-meter square area. In both instances, the center of area A is point L at which the snap state error is determined.

The shape of the calculated area is not particularly important. However, one shape may better accommodate other characteristics of the mobile robot, such as the shape of the robot and/or the pattern in which the robot is programmed to travel. Figures 8 and 9 show the robotic vacuum cleaner traveling in a square spiral pattern; however other patterns of travel will be apparent. The circular calculated area A shown in FIG. 8 may be more suitable for a robot following a spiral travel pattern such as an Archimedes spiral, while the square calculated area may be more suitable for following a square A helical pattern (such as the embodiment shown in Figure 9) or other regular linear pattern of travel for the robot.

The purpose of a robotic vacuum cleaner is to provide a high level of cleaning performance, and thus it is important that the vacuum cleaner resumes cleaning in its full power mode as quickly as possible, but with the smallest possible probability of immediately repeating a suction state error. Thus, the size of the calculated area is predetermined and takes into account the need for the vacuum cleaner to return to full power as quickly as possible and the probability level that the robot has left the area of the floor surface causing the adsorption state error. Through a process of trial and error and statistical analysis, this predetermined size has been chosen to be a 1 meter square area for a robotic vacuum cleaner tasked with cleaning a domestic environment. However, different sized areas may be more suitable for mobile robots performing different tasks and/or jobs within different environments.

Once the robot travels outside the calculated area, the error handling operation stops and the robot resumes cleaning operation under normal conditions at full power. In Figures 8 and 9, the point at which the robot leaves the calculated area and resumes the cleaning process at full power is given by indication and are marked with the reference letter F. In Figure 8, the suction state error is detected at the beginning of the travel pattern, whereas in Figure 9 the suction state error is detected halfway around the square helical path of the robot. Thus, the length of the path for the robot to operate in low power mode (ie between the marked points L and F) is much longer in FIG. 8 than in FIG. 9 . This is used to emphasize that simply running the robot vacuum in low power mode for a predetermined length of time may not be suitable for deactivating a snap state error, as the length of time does not necessarily correspond to the distance traveled from a point, especially when the robot is configured to follow the When traveling in a spiral path.

Once the robot leaves the calculated area and resumes cleaning operations at full power, the calculated area is discarded. Thus if the robot re-enters a previously calculated area, there will be no change and the power will remain at full power. This behavior is to facilitate optimum cleaning performance for the largest possible proportion of the area to be cleaned. The robot will only enter low power mode if a new case of snap state error is determined again. This new instance of snap state error will be handled in exactly the same way as the first time, where a new region of predetermined size is calculated for the second instance of snap state error. Alternatively, it may be advantageous in certain circumstances for the robot to store the calculated area in memory after it has exited the calculated area, and to resume low power mode when it detects that it has re-entered a previously calculated area.

While particular examples and embodiments have been described, it will be understood that various modifications may be made without departing from the scope of the invention as defined in the claims. The method of detecting errors as described above can be employed by devices other than mobile robots such as vacuum cleaners, hair care appliances and other consumer electronics. As the cost of microprocessors and other types of central processing units (CPUs) decreases, and as the level of intelligence expected by users in other consumer products increases, more and more devices will incorporate intelligent control systems. By including control systems (such as those described above) in these devices, the number of sensors required in the device can be reduced, and as such the cost of the device can be minimized.

Claims (19)

1. A method of controlling a mobile robot, the method comprising: monitoring a first system of the mobile robot to detect a first error associated with the first system; and monitoring a second system of the mobile robot to detect a second error associated with the second system; Wherein when the first error and the second error are detected simultaneously, it is determined that the third error has occurred. 2. The method of claim 1, further comprising causing the robot to perform an error handling operation in response to a determination that a third error has occurred. 3. The method of claim 2, wherein the error handling operation performed in response to the third error is different than the alternate error handling operation performed in response to one of the first or second errors. 4. A method as claimed in any one of the preceding claims, wherein the first system is a floor cleaning system and includes a motor for generating air flow through the mobile robot. 5. The method of claim 4, wherein the first error is an airway blockage. 6. A method as claimed in claim 4 or 5, wherein the detection of the first error comprises detecting a reduction in the load experienced by the motor. 7. The method of any one of the preceding claims, wherein the second system is a drive system and includes one or more navigation sensors and drive actuators, the navigation sensors being used to monitor the robot's movement in the environment position, and the drive actuators are used to move the robot in the environment. 8. The method of claim 7, wherein the second fault is a skid. 9. A method as claimed in claim 7 or 8, wherein the step of monitoring the second system comprises monitoring changes in the position of the robot as the robot is driven. 10. A method as claimed in claim 9, wherein the detection of the second error comprises detecting that the change in position of the robot detected by the one or more navigation sensors does not correspond to an amount driven by the drive actuator. 11. A method as claimed in any one of the preceding claims, wherein the third error is the adsorption state of the robot. 12. A method as claimed in any one of claims 2 to 11, wherein the first system comprises a motor for generating air flow through the mobile robot, and wherein in response to a determined error that a third error has occurred Treatment operations include running the motors in a reduced power mode to reduce suction and continue to drive the robot. 13. The method of claim 12, wherein the motor is operated in a reduced power mode until the mobile robot has traveled outside a calculated area of predetermined size, the center of which is the first Three errors are detected at the location. 14. A method as claimed in any one of the preceding claims, wherein if one or the other of the first or second errors persists while the other of the first or second errors is detected, Then the first error and the second error are detected simultaneously. 15. A mobile robot comprising a control system, a task performance system and a drive system, the control system being configured to monitor the task performance system and the drive system, wherein the control system comprises an error detection unit, the error detection unit being controlled by Configured to detect a first error in the task performance system and a second error in the drive system, and further configured to determine that a third error has occurred if it detects both the first error and the second error. 16. The mobile robot of claim 15, wherein the control system further comprises an error handling unit configured to execute a corresponding first or second error in response to detection of the first or second error one of the processing operations and is further configured to instead perform a third error handling operation in response to a determination that a third error has occurred. 17. A mobile robot as claimed in claim 15 or 16, wherein the task performance system is a floor cleaning system comprising a motor for generating air flow through the mobile robot. 18. The mobile robot according to claim 17, wherein the first error is blockage of the air passage, the second error is slipping, and the third error is the adsorption state of the mobile robot. 19. An error detection unit for a mobile robot, the error detection unit comprising: a monitoring unit for monitoring one or more parameters of the first and second systems of the mobile robot and identifying one or more parameters of the first and second systems indicative of an error, and an error determination unit capable of determining: if the monitoring unit identifies a parameter of the first system indicating an error, then the first error has occurred; if the monitoring unit identifies a parameter of the second system indicating an error, then the second error has occurred; and if the monitoring unit simultaneously Identify the parameters of the first and second systems indicating errors then a third error has occurred.